Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P08908 (5-HT1A)
 5,574 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pharmacological characteristics of hindlimb scratching induced by serotonergic compounds were studied. We conclude that hindlimb scratching induced by serotonergic compounds is mediated by a serotonin1D (5-HT1D) or 5-HT1D-like receptor outside the blood-brain barrier because hindlimb scratching could be induced by s.c. injection of 5-methoxytryptamine (5-MeOT), 5-carboxamidotryptamine (5-CT), bufotenine, 5-hydroxytryptamine (5-HT) and tryptamine. These compounds have high affinity for 5-HT1A and 5-HT1D receptors. The 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), the 5-HT1C receptor agonist MK 212, and the mixed 5-HT1C/5-HT2 receptor agonists (dl)-1-(2,5 dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and quipazine did not induce hindlimb scratching. Rather, the latter compounds attenuated 5-MeOT-induced hindlimb scratching. The 5-HT releasing compounds fenfluramine and p-chloroamphetamine (PCA) inhibited whereas the 5-HT re-uptake inhibitors fluvoxamine and indalpine potentiated 5-MeOT-induced hindlimb scratching. 5-MeOT-induced hindlimb scratching could be inhibited dose dependently by the alpha 2-adrenoceptor blockers yohimbine and rauwolsince, which also have high affinity for 5-HT1D receptors, whereas the alpha 2-adrenoceptor blocker piperoxan only weakly counteracted hindlimb scratching. Haloperidol, apomorphine, morphine, clonidine and methiothepin strongly attenuated hindlimb scratching, atropine, naloxone and ICS 205930 attenuated it weakly whereas domperidone, methylatropine and mepyramine were inactive in doses up to 10 mg/kg. Hindlimb scratching induced by 5-MeOT was potentiated by the 5-HT receptor antagonists metergoline, methysergide, mesulergine, mianserin, ritanserin and xylamidine. Hindlimb scratching was not induced by i.c.v. injection of 5-MeOT.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A peripheral 5-HT1D-like receptor involved in serotonergic induced hindlimb scratching in rats. 206 Jun 1

We review our results from the first computational simulations of a mechanism by which ligands can activate a 5-HT1A receptor, and relate the findings to information on the structure and function of the authentic receptor. The computational exploration of the recognition and activation mechanisms is carried out inside a protein selected as a model for the receptor based on cognate physicochemical and experimental data. A similar approach is applied to the 5-HT2 receptor. The interaction mechanisms at the two 5-HT receptor subtypes differ in the nature of the forces determining ligand-receptor interactions and the types of receptor activation mechanisms they entail. The main molecular property related to recognition at 5-HT1A receptors was shown to be the directional character of the electrostatic potential generated by the ligands in the molecular region corresponding to the indole in 5-HT. The corresponding recognition site was shown to have properties of a positively-charged (imidazolium) form of the side chain of a His residue. The mechanism of recognition at the 5-HT1A receptor was shown to be electrostatic, and conducive to a triggering of the receptor response through the change in the electronic structure of the imidazolium recognition site when it interacts with an activating ligand (agonist). This effect was shown to induce a proton transfer from the ring to a neighboring residue to which it can be hydrogen-bonded in the resting state. We show how this model for recognition and activation defines in molecular terms the mechanisms underlying the classical pharmacologic properties of agonists, partial agonists, and antagonists. The molecular correlates of pharmacologic efficacy emerge from the calculations of the effect of the ligands on the barriers for proton transfer, and on the energy drive for the proton transfer reaction. A different model is proposed for selective recognition at the 5-HT2 receptors, based on structural details of 5-HT-binding peptides. The recognition site is considered to consist of two aromatic residues separated by a hydrophilic residue. In contrast to the model for 5-HT1A, the recognition is based on the interaction of neutral molecules and the stabilization is provided by dispersion forces. The resulting activation mechanism is based on a structural rearrangement. These detailed descriptions of elements in the ligand-receptor interactions at the two receptor subtypes lead to a new basis for rational design of receptor-selective compounds with predetermined efficacy.
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PMID:On the structural and mechanistic basis of function, classification, and ligand design for 5-HT receptors. 207 75

5-Hydroxytryptamine (5-HT) receptors have been analyzed and related to potential roles played by 5-HT in the physiology of the enteric nervous system (ENS). Three subtypes of 5-HT receptor--5-HT1P, 5-HT3, and 5-HT1A--have been found on enteric neurons. Receptors have been identified by intracellularly recording the electrical activity of enteric neurons and by studying the binding of radioligands and polyclonal anti-idiotypic antibodies raised against antibodies to 5-HT. Radioligand binding has been assessed by rapid filtration and by radioautography. 5-HT1P receptors mediate slow depolarizations of myenteric neurons that are associated with a closure of K+ channels. These responses can be inhibited by N-acetyl-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP) and by the substituted benzamide, BRL 24924. 5-HT1P-like responses can be mimicked by 5- and 6-hydroxyindalpine, by another substituted benzamide, the S stereoisomer of zacopride, and by anti-idiotypic antibodies. 5-HT1P receptors can be labeled by 3H-5-HT and 3H-5-hydroxyindalpine with high affinity and are located on neurons of both enteric plexuses and on processes of intrinsic neurons in the gastrointestinal mucosa. A similar distribution of binding sites for anti-idiotypic antibodies is revealed by immunocytochemistry. Excitatory postsynaptic potentials (EPSPs) mediated by 5-HT are abolished by 5-HT1P antagonists. Blockade of 5-HT1P receptors is accompanied by acceleration of the rate of gastric emptying. Mucosal application of cholera toxin activates enteric neurons in both plexuses; this action is blocked by 5-HT1P or 5-HT3 antagonists and by anti-idiotypic antibodies. 5-HT3 receptors are responsible for fast depolarizations associated with increased membrane conductance. These responses are antagonized by ICS 205-930 and mimicked by 2-methyl-5-HT and anti-idiotypic antibodies. 5-HT1A receptors have been reported to mediate hyperpolarizing responses associated with a rise in membrane conductance. Hyperpolarizing responses are also elicited by the 5-HT1A agonists, 8-hydroxy-di-n-propylaminotetralin (8-OH-DPAT) and 5-carboxyamidotryptamine. It is proposed that 5-HT1P receptors and perhaps 5-HT3 receptors are involved in initiating the peristaltic reflex and in regulating gastric emptying. No physiologic role has yet been identified for 5-HT1A receptors in the ENS.
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PMID:5-HT receptor subtypes outside the central nervous system. Roles in the physiology of the gut. 207 74

The functional role of brain 5-HT and 5-HT receptor subtypes in periaqueductal gray (PAG) induced aversion has been investigated in rats. Antiaversive effects were found with the serotonin agonists TFMPP, mCPP and DOI but not with RU 24969 which was found to facilitate PAG aversion. The first three serotonin agonists share potent 5-HT1C activity while RU 24969 differs with a high 5-HT1A activity. Proaversive effects were found with the mixed 5-HT1C/5-HT2 antagonists cyproheptadine and ritanserin; this effect was already reported for the mixed 5-HT1C/5-HT2 antagonists metergoline and mianserin and is opposite to the effects of the selective 5-HT2 antagonists ketanserin, pirenperone, trazodone and spiperone. The antiaversive effects of mCPP (1 mg/kg) could be prevented by pretreatment of the animals with mianserin (1 and 10 mg/kg). These results suggest that 5-HT1C receptors play an important role in the serotonergic control of PAG aversion. 5-HT1C receptor activation seems to mediate antiaversive effects whereas acute 5-HT1C receptor blockade appears to facilitate PAG aversion. Functional interactions take place between several receptor types in the in vivo control of PAG aversion, where 5-HT1C receptors appear to play a predominant function.
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PMID:5-HT1C receptors in the serotonergic control of periaqueductal gray induced aversion in rats. 210 58

The 5-hydroxytryptamine (5-HT) receptor mediating endothelium-dependent relaxation of pig coronary arteries was characterized using a variety of 5-HT receptor agonists and antagonists. Unrubbed (with endothelium preserved) rings precontracted by prostaglandin F2 alpha in the presence of ketanserin relaxed in an endothelium-dependent manner to 5-HT, 5-carboxamidotryptamine and 5-methoxytryptamine with about equal potency and efficacy. By comparison, bufotenine, 3-(dimethylamino)ethyl-N-methyl-1H-indole-5-methane sulfonamide, (-)-alpha-methyl-5-HT,N,N-dipropyl-5-carboxamidotryptamine and 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H indole were half-efficient and other drugs [in particular the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin] were inactive as agonists up to 0.1 mM. The effect of 5-carboxamidotryptamine was antagonized in an apparently competitive manner by 15 drugs. Among the most potent antagonists (mean pKB value) were the nonselective 5-HT receptor antagonists, methiothepin (7.30) and metergoline (6.86), the 5-HT1A/5-HT1D receptor ligand, 1-[2-(4-amino-phenyl)ethyl]-4-(3-trifluoromethylphenyl)-piperazine (7.02), the 5-HT1A/5-HT1B/5-HT1D receptor ligand, 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo[1,2,-a]quinoxaline 1 (6.73) and yohimbine (6.37). Selective ligands for 5-HT1A receptors were either inactive [8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide] or poorly active (spiperone, 4.44). Beta-adrenoceptor antagonists with affinity for 5-HT1A and 5-HT1B receptors weakly antagonized the effect of 5-carboxamidotryptamine (pKB values less than or equal to 5.32), as did the 5-HT1c/5-HT2 receptor antagonist, mesulergine (5.30) and the yohimbine isomer, corynanthine (4.85). Methysergide was clearly a noncompetitive antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:5-Hydroxytryptamine (5-HT)-induced endothelium-dependent relaxation of pig coronary arteries is mediated by 5-HT receptors similar to the 5-HT1D receptor subtype. 213 76

The purpose of the present study was to characterize the cardiorespiratory effects of activation of 5-HT1A, 5-HT1B and 5-HT2 receptor subtypes at the intermediate area of the ventral surface of the medulla. The agonists (+/-)-8-hydroxy-2-(di-N-propylamino)tetralin hydrobromide (8-OH-DPAT), 1-[3-(trifluoromethyl)phenyl]-piperazine hydrochloride (TFMPP) and (+/-)-1-(2,5-di-methoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI) were used to activate these receptor subtypes, respectively. Application of each drug to the intermediate area produced a different profile of cardiorespiratory effects. 8-OH-DPAT (0.0625-4.0 micrograms) produced dose-dependent hypotension and bradycardia, which were antagonized by the 5-HT1A antagonists spiperone and spiroxatrine. The bradycardia was blocked by bilateral vagotomy. No significant changes in respiratory motor outflow to the larynx or diaphragm were observed after application of 8-OH-DPAT. TFMPP (10-1000 micrograms) also produced a dose-dependent hypotension and bradycardia. However, these effects were not antagonized by spiperone or blocked by vagotomy. A decrease in the amplitude of the recurrent laryngeal and phrenic nerve signals was observed after application of the highest dose of TFMPP. In contrast to the effects of 8-OH-DPAT and TFMPP, DOI (0.3-100 micrograms) produced an increase in blood pressure without any change in heart rate. Recurrent laryngeal and phrenic nerve activities were depressed, as was respiratory rate, after application of DOI. Both the cardiovascular and respiratory effects of DOI were blocked by the 5-HT2 antagonist ketanserin. These results indicate that activation of ventral medullary 5-HT receptor subtypes produces unique effects on cardiorespiratory activity.
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PMID:Characterization of the effects of activation of ventral medullary serotonin receptor subtypes on cardiovascular activity and respiratory motor outflow to the diaphragm and larynx. 213 22

The effects of 5-hydroxytryptamine (5-HT) receptor agonists on calcium (Ca2+)-stimulated adenylate cyclase activity in the hippocampus and cerebral cortex of the rat were studied. In the presence of Ca2+ (1.5 microM), 5-HT dose dependently inhibited adenylate cyclase activity (EC50 = 10 +/- 2 nM). The inhibitory effect of 5-HT on Ca2(+)-stimulated adenylate cyclase was antagonized by spiperone (KB = 2 +/- 0.8 nM). The rank order of potency of 5-HT agonists to inhibit Ca2(+)-stimulated adenylate cyclase in the hippocampus was: 5-carboxamidotryptamine (5-CT) greater than 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) greater than 5-hydroxytryptamine (5-HT) = 5-methoxytryptamine (5-OCH3-T) greater than trifluoromethylphenylpiperazine (TFMPP) greater than m-chlorophenylpiperazine (mCPP). 2-Methyl-5-hydroxytryptamine (2-CH3-5-HT) did not exert an effect on Ca2(+)-stimulated enzyme activity. In the cerebral cortex 5-HT exerted a biphasic stimulatory effect on adenylate cyclase activity in the absence of Ca2+ (EC50 = 0.2 +/- 0.04 nM and 10 +/- 3 microM), whereas 8-OH-DPAT, 5-CT and 2-CH3-5-HT exerted a monophasic effect. In the presence of Ca2+ (1.5 microM), low concentrations of 5-HT, 8-OH-DPAT, 5-CT and 2-CH3-5-HT potentiated adenylate cyclase activity, whereas higher concentrations, except 2-CH3-5-HT, inhibited the enzyme activity. We propose that the 5-HT receptor mediating inhibition of Ca2(+)-stimulated adenylate cyclase in the rat hippocampus corresponds to the 5-HT1A subtype.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:5-Hydroxytryptamine receptor agonists influence calcium-stimulated adenylate cyclase activity in the cerebral cortex and hippocampus of the rat. 213 81

The long-term effects of low doses of the 5-HT1A-agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), were studied to assess differences in the development of subsensitivity in 8-OH-DPAT-induced behavioural responses. Male rats received 33 or 100 micrograms/kg per day s.c. for 8 or 15 days. The chronic treatment did not alter the facilitatory effects of 8-OH-DPAT on male copulatory behaviour. In contrast, the effects on exploratory activity and the induction of flat body posture observed after the acute treatment were attenuated by prolonged administration of 8-OH-DPAT. The results presented indicate that gonadal hormones are involved in 5-HT receptor regulatory mechanisms.
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PMID:The long-term effects of 8-hydroxy-2-(di-n-propyl-amino)tetralin (8-OH-DPAT) on copulatory and exploratory behaviour in male rats. 213 13

Subcutaneous injections of a 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), in monkeys induced distinct behavioural changes characterized by head weaving, hindlimb extension and upper limb fluttering. The effects were dose-dependent and were similar to the 5-HT syndrome induced in rats by 8-OH-DPAT. The 5-HT receptor antagonist, metergoline, attenuated the behavioural syndrome seen in response to 8-OH-DPAT. These results suggest that 8-OH-DPAT induces a 5-HT1A receptor-mediated behavioural syndrome in monkeys as well as in rodents.
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PMID:Behavioural effects of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) in monkeys. 213 14

The effects of serotonin on the membrane potential of primary afferent terminals of isolated hemisected frog spinal cords was investigated by sucrose gap recordings from dorsal root. Serotonin produced two distinctive changes in primary afferent terminal membrane potential: modest (about 0.5 mV) hyperpolarizations in low concentrations (0.01-1.0 microM) and larger (about 1.0 mV) slow depolarizations in higher concentrations (3.0-100 microM). The hyperpolarizations appeared related to a direct activation of 5-HT1A receptors on afferent terminals. The depolarizations were attributed to both direct and indirect actions and appeared to be generated by activation of 5-HT2 and/or 5-HT1C receptors. The results suggest that 5-HT released from terminals in the frog dorsal horn could exert a modulatory action on the afferent input of the spinal cord, but different effects generated by activation of different 5-HT receptor subtypes are dependent upon the concentration of the amine.
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PMID:An in vitro study of the effects of serotonin on frog primary afferent terminals. 214 2


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